The present invention relates to thermal insulation of walls, and more particularly to systems for supporting rigid insulation in structural framing applications.
Walls of buildings may include framing made of light gauge steel, wood, or a combination thereof. In addition to structural requirements that the framing must meet, thermal characteristics are important, especially for exterior walls. Minimizing heat transfer through the walls is desirable both for comfort and for energy efficiency of heating and air conditioning. For example, when the outdoors is cold relative to inside a heated structure, heat from indoors should be prevented from passing through the walls to the outdoors. Conversely, when the outdoors is hot relative to inside an air conditioned structure, heat from outdoors should be prevented from passing through the walls to the inside. The degree of prevention of heat transfer may be based on considerations of technical feasibility as well as cost.
Heat transfer through walls may be addressed in a variety of ways. Framing may include a top plate, a bottom plate or sill, vertical posts or studs, and mid-section blocking, among other components. Spun fiberglass insulation is commonly placed in the cavities formed by the framing components. Rigid insulation sheets or panels, such as those made from expanded or extruded polystyrene or polyisocyanurate, may also be used. Another method is to inject foam insulation into the cavities. While each of these methods reduces conduction of heat through the areas between framing components, they generally do not address conduction through the components themselves, which may present a direct and continuous path for heat transfer across the wall.
Several known designs for insulating walls with metal members attempt to minimize heat transfer by using rigid insulation. The metal members may be, among other things, “C” shaped in cross-section, meaning having a web, first and second flanges generally perpendicular to the web, and returns on each flange, or “U” shaped in cross-section, having a web and first and second flanges generally perpendicular to the web, without returns. The flanges of the members are sometimes embedded in the rigid insulation in slots that are formed by “hot-wiring” the insulation. Such construction adds to the complexity of manufacturing and fabrication, and limits the ability to make on-site modifications.
For the foregoing reasons, there exists a need for a framing system that supports rigid insulation to limit heat transfer through a wall, is relatively easy and quick to install, and may allow field modifications.